Determination of stable molybdenum isotopes by thermionic mass spectrometry for tracer studies of molybdenum plant metabolism

A tracer technique based on multiple stable Mo isotopes and thermionic quadrupole mass spectrometry for isotopic analysis of plant tissue was developed and has been applied in the long-term study of foliar absorption of Mo by potato plants. As several tracers have been used the multivariate linear regression methods has been applied to calculate the portions of tracer Mo present in the potato samples from the isotopic ratios measured and to estimate their reproducibilities.In this paper solely the tracer portions transferred from the leaf into the tuber of the potato have been determined. Dependent on the time of contamination, tracer portions of 0.2 to 12% have been measured, corresponding to a maximum of 2.3% of the foliar application of the tracer molybdate. The reproducibilities of the tracer method as a whole (analytical determination and calculation of the tracer portions in the tracer plant samples) amounted to 7% at the maximum (with one exception); by contrast, the individual differences between the three plants investigated were much larger (up to 80%).     

SIMS determination of the distribution of the main mineral cations in the depth of the cuticle and the pecto-cellulosic wall of epidermal cells of flax stems: problems encountered with SIMS depth profiling

Depth profiles of C, Na, Mg, Al, K and Ca were performed in the cuticle and wall of epidermal cells of flax hypocotyls, with current densities ranging from 0.2 to 1 pA μm^?2. The crater bottoms were never flat, but exhibited fairly complex, filiform or alveolar structures. The profiles of K, Ca and Mg were reasonably parallel to one another. The Ca/Mg signal ratio was in the magnitude of 3.5 in the cuticle. The Na profile, except perhaps in the cuticle, did not parallel the K, Ca and Mg profiles, but rather paralleled the C profile. At the outset of the depth profiles, ie in the cuticle, the intensity of the Na signal, although fairly variable, was usually above that of K; then there was an abrupt decrease of the Na signal, possibly at the border of the cuticle and of the wall. The Al signal usually began to increase, thus revealing the occurrence of perforations through the epidermis sample, after 80 min sputtering at a current density of 1 pA μm^?2; the mean sputtering rate was thus estimated to be in the order of 1 μm h^?1.     

Determination of the elemental composition of mature wheat grain using a modified secondary ion mass spectrometer (SIMS)

An imaging secondary ion mass spectrometry system has been developed that allows the distribution of elements or ions to be superimposed on an image of the plant cell or tissue generated by ion-induced secondary electrons. This system has been evaluated by analysing the aleurone and sub-aleurone cells of mature wheat grain, showing high spatial resolution (100-200 nm) images of O-, PO(2)-, Mg+, Ca+, Na+ and K+ within the phytate granules of the aleurone, with CN- being diagnostic for proteins and C(2)- being diagnostic for starch in the starchy endosperm cells. This system should provide improved localization of elements in a range of other plant systems.     

超声在植物生理学领域的应用

综述了超声在植物生理学研究和实践中的应用。研究涉及超声对植物体呼吸强度、萌发率、生根状况、某些代谢途径的影响以及超声的空化作用对植物体生理学方面的影响。在植物生理学领域中超声的应用主要是利用了超声的空化作用、机械作用和热效应。     

Zinc metabolism and homeostasis: The application of tracer techniques to human zinc physiology

Tracer kinetic techniques based on zinc stable isotopes have a vital role in advancing knowledge of human zinc physiology and homeostasis. These techniques have demonstrated the complexity of zinc metabolism, and have been critical to estimating the size and interrelationships of those pools of zinc that exchange rapidly with zinc in plasma and which are likely to be especially important for zinc dependent biology. This paper presents findings from recent research linking a steady state compartmental model with non-steady state post-prandial sampling from the intestine, utilizing a combination of intestinal intubation/perfusion and stable isotope tracer kinetic techniques. The gastrointestinal tract has a central role in maintaining whole body zinc homeostasis. While the fractional absorption of zinc from a meal depends on the quantity of exogenous zinc and on such dietary factors as phytic acid, the fractional absorption does not appear to be dependent on the size of the rapidly exchanging pool of the host. In contrast, the quantity of endogenous zinc excreted via the intestine is positively correlated with both the amount of absorbed zinc and the zinc `status' of the host, and thus this process has an equally critical role in maintaining zinc homeostasis. The observed alterations in zinc metabolism in some disease states can be understood in the context of known homeostatic processes. In other conditions, however, such alterations as inflammation-associated hyperzincuria and zinc redistribution, the links between homeostatic perturbation and cellular biology are yet to be explained. Thus the challenge remains for research at the whole body level to carefully characterize zinc distribution and exchange under diverse circumstances, while research at the cellular level must elucidate the regulatory processes and the factors to which they respond.     

研究性教学模式在"植物的抗逆生理"教学中的应用

阐述了研究性教学的内涵及将之引入"植物的抗逆生理"教学的必要性,并介绍了开展研究性教学活动过程,评价了其教学效果.在此基础上就研究性教学模式下研究专题的选择、学生的成绩考核指标及教师扮演的角色等内容进行了讨论.     

Comparison of lag times in plant physiology

Abstract Comparison of lag (or latent) times is a useful tool in plant physiology for investigating potential mechanisms involved in a response. There are two main ways of deriving the lag time, but only one of these can be properly used for comparative purposes. The other method is biased by the faster responding plants and may not give a representative estimate for the lag time in the population. The fact that the two methods give different, non-comparable results has been widely overlooked. We suggest more care should be taken for their correct use, and propose two terms which can be used to describe the different estimates of the lag time to avoid confusion.     

植物代谢组学中几种重要的次生代谢物液质分析技术研究进展

代谢组学（metabolomics）主要是研究生物体、组织、细胞的代谢物组分及检测其动态变化过程,是继基因组和蛋白组学后新兴的一门组学技术。代谢物是细胞调节过程中的最终产物,其水平被视为生物系统对遗传或环境变化的最终反映。通过合适的分析平台,准确定性、定量在复杂的生物中具有化学多样性的次生代谢物是代谢组学的一项重要工作。液相色谱-串联质谱技术（liquid chromatography-tandem mass spectrometry,LC-MS/MS）是代谢物质检测平台最常用的方法,也为植物次生代谢物的广泛应用研究提供了基础。本文主要从植物激素类、叶酸类、黄酮类等次生代谢物方面进行阐述,结合液质联用技术,简要论述不同次生代谢物检测技术的研究进展。     

From Charles Darwin's botanical country-house studies to modern plant biology

As a student of theology at Cambridge University, Charles Darwin (1809–1882) attended the lectures of the botanist John S. Henslow (1796–1861). This instruction provided the basis for his life-long interest in plants as well as the species question. This was a major reason why in his book On the Origin of Species , which was published 150 years ago, Darwin explained his metaphorical phrase 'struggle for life' with respect to animals and plants. In this article, we review Darwin's botanical work with reference to the following topics: the struggle for existence in the vegetable kingdom with respect to the phytochrome-mediated shade avoidance response; the biology of flowers and Darwin's plant–insect co-evolution hypothesis; climbing plants and the discovery of action potentials; the power of movement in plants and Darwin's conflict with the German plant physiologist Julius Sachs; and light perception by growing grass coleoptiles with reference to the phototropins. Finally, we describe the establishment of the scientific discipline of Plant Biology that took place in the USA 80 years ago, and define this area of research with respect to Darwin's work on botany and the physiology of higher plants.     

Julius Sachs (1868): The father of plant physiology

The year 2018 marks the 150th anniversary of the first publication of Julius von Sachs' (1832–1897) Lehrbuch der Botanik (Textbook of Botany), which provided a comprehensive summary of what was then known about the plant sciences. Three years earlier, in 1865, Sachs produced the equally impressive Handbuch der Experimental‐Physiologie der Pflanzen (Handbook of Experimental Plant Physiology), which summarized the state of knowledge in all aspects of the discipline known today as plant physiology. Both of these books provided numerous insights based on Sachs' seminal experiments. By virtue of a reliance on detailed empirical observation and the rigorous application of chemical and physical principles, it is fair to say that the publication of these two monumental works marked the beginning of what can be called “modern‐day” plant science. Moreover, Sachs' Lehrbuch der Botanik prefigured the ascendance of plant molecular biology and the systems biology of photoautotrophic organisms. Regrettably, many of the insights of this great scientist have been forgotten by the generations who followed. It is only fitting, therefore, that the anniversary of the publication of the Lehrbuch der Botanik and the career of “the father of plant physiology” should be honored and reviewed, particularly because Sachs established the physiology of green organisms as an integral branch of botany and incorporated a Darwinian perspective into plant biology. Here we highlight key insights, with particular emphasis on Sachs' detailed discussion of sexual reproduction at the cellular level and his endorsement of Darwinian evolution.     

Investigating the Effects of Chemical Gradients on Performance and Reliability within Perovskite Solar Cells with TOF‐SIMS

Time‐of‐flight secondary‐ion mass spectrometry (TOF‐SIMS), a powerful analytical technique sensitive to all components of perovskite solar cell (PSC) materials, can differentiate between the various organic species within a PSC absorber or a complete device stack. The ability to probe chemical gradients through the depth of a device (both organic and inorganic), with down to 100 nm lateral resolution, can lead to unique insights into the relationships between chemistry in the absorber bulk, at grain boundaries, and at interfaces as well as how they relate to changes in performance and/or stability. In this review, the technique is described; then, from the literature, several examples of how TOF‐SIMS have been used to provide unique insight into PSC absorbers and devices are covered. Finally, the common artifacts that can be introduced if the data are improperly collected, as well as methods to mitigate these artifacts are discussed.     

植物水分利用策略研究进展

水分是影响植物生长发育的重要因子之一。地球上大多数生态系统中的植物都会经历一个降水相对稀少的干旱季节,植物在不同的季节与不同的生态系统中究竟如何利用水分,利用哪些水分去获得生存,成为一个人们关注的问题。在过去的20年,稳定同位素技术在植物生态学中的应用得到了稳定长足的发展。因为陆地植物(少数排盐种类除外)在水分吸收过程中不发生同位素分馏,因此可以利用δD与δ18O数据进行水分获取方式的研究。对植物木质部水分以及其潜在水源的稳定同位素进行分析,并参考土壤水势、叶片水势、土壤含水量等数据,同时运用二元或三元混合模型,可以定量确定植物的水分利用来源。大量的研究表明,不同功能型、生长阶段、季节的植物以及不同物种往往具有不同的水分利用策略。     

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)₃]²⁺ (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.     

植物衰老期间生理生化变化的研究进展

植物衰老是受内外因素控制的细胞有序降解并最终导致死亡的过程,衰老期间会出现与正常生长阶段不同的生理生化变化。植物衰老引起的各种功能的下降极大地限制了作物产量潜力的发挥,种子贮存过程中的衰变、逆境条件下植株的早衰、果蔬采后贮藏衰老导致货架寿命的缩短等均会造成极大的经济损失。研究植物衰老的生理机制及其调控具有十分重要的意义。综述了有关植物衰老时生理生化变化方面的近期研究进展,以利于人们对植物衰老生理的更深入的了解。     

“植物抗性生理”一章的教学方法探讨

植物抗性生理主要研究植物在各种不良环境条件下的生理特征。为了提高＂植物抗性生理学＂一章的教学效果,从学生实际出发,在6个方面阐述了本章的教学方法和手段。     

Imaging the K,Mg, Na and Ca Distributions in Flax Seeds using SIMS Microscopy

Taking advantage of the sensitivity, the lateral resolution and the ability of secondary ion mass spectrometry (SIMS) for elemental imaging, we have shown that the main alkaline and alkaline-earth cations exhibited clear-cut regionalization in flax seeds. Calcium, and even more magnesium were almost exclusively located within the protein bodies (PBs); and they were practically absent from the tissue areas with no PBs, such as the provascular tissue. By contrast, sodium was almost exclusively located outside the PBs; moreover, most of the seed sodium was in the tissues at the seed periphery (chiefly the teguments). Among the studied cations, potassium was the only one with a non-negligible concentration both in and outside the PBs.     

The role of ion channels in plant nutrition and prospects for their genetic manipulation

Ion channels can function in three physiological modes through their ability to: 1) accommodate osmotically significant fluxes over short periods; 2) propagate signals along or across membranes; 3) control the membrane potential. With respect to mineral nutrition it is via the control of the membrane potential that ion channels are probably most significant. In this paper the physiology and prospects for molecular biology of plant ion channels are discussed. It is concluded that identifying and altering the primary structures that determine functional characteristics of plant ion channel genes could result in changes in the transport characteristics of higher plants.     

植物呼吸释放CO2碳同位素变化研究进展

稳定性碳同位素是研究碳循环的有效手段。植物呼吸释放CO_2的碳同位素(δ~(13)C_R)变化是研究植物或生态系统与大气碳交换的重要方法,并可以揭示植物的生理过程、碳分配方式及其对环境变化的响应。介绍了目前国内外关于植物δ~(13)C_R变化的研究概况,植物不同器官δ~(13)C_R值及其日变化幅度趋势一致:叶片根系树干/茎,不同功能群植物其呼吸释放CO_2碳同位素组成存在差异。但植物δ~(13)C_R值日变化与呼吸底物的相关性在不同的研究中结果并不一致。导致植物呼吸δ~(13)C_R发生变化的主要原因为光合同位素效应、呼吸底物的供给及呼吸代谢中间产物利用、碳代谢相关酶的活性、LEDR(light enhanced dark respiration)、植物的遗传特性及外部环境改变。目前国际上已有较多关于导致植物呼吸δ~(13)C_R发生变化原因的研究,但内在机制的研究尚未完善。该领域研究在国内鲜有报道,因此,亟需加强我国关于植物δ~(13)C_R短期变化及其潜在呼吸代谢机制的研究。     

植物生理学双语教学的实践与创新

对近几年来植物生理学课程双语教学内容、教学方法、教学手段及考核方式等方面的改革进行了较深入的探讨与实践。通过研制双语教学网络课件,选择正确的国外原版教材和国内教材、编写合适的双语教学讲义,采用形式多样的双语教学模式,正确处理专业词汇和建立有效的考核机制等途径来提高双语教学质量,实现教学目标。